MORPHOLOGY:
This species could be considered an intermediate form between the tamarins and marmosets and the cebids. The Goeldi’s marmoset has claws instead of nails, except for the hallux, which has a nail (Heltne et al., 1981), like the marmosets, and three molar teeth, which is like the cebids. Also like the cebids the molars are quadritubercular (Heltne et al., 1981). This species has a dental formula of 2:1:3:3 on both the upper and lower jaws (Heltne et al., 1981). The scapula is unique in shape having the superior scapular border and the spinous process parallel in length, and this may assist in quadrupedal locomotion (Davis, 1994). The pelage color for this species is black, and the pelage ranges from 1 to 2 centimeters long over the body (Heltne et al., 1981). The skin of lips, snout, rims of ears, and the dorsal and volar surfaces of the hands and feet are colored black, with the skin of face being slightly lighter in color (Heltne et al., 1981). The remaining skin is colored bone-white or pink, but is usually covered by thick pelage (Heltne et al., 1981). Around the ears and going down the cheeks to the lips are hairs longer than found on the face (Heltne et al., 1981). The infant pelage may vary from the adult's in that the saddle hairs may have a whitish or golden terminal band (Heltne et al., 1981). Also on the ventral surface of the infant there is a glandular area over the manubrium containing hairs that are slightly longer than the other hairs found on the ventral surface (Heltne et al., 1981). The mean body mass for adult males was found to be 366 grams and for females it is 355 grams (Encarnacion and Heymann, 1998).

RANGE:
The Goeldi’s marmoset is found in the upper Amazonian rainforests of Southern Colombia, Eastern Ecuador, Eastern Peru, Western Brazil, and Northern Bolivia (Nowak, 1999). This species is found from the south bank of the Caqueta River in Colombia, through the Amazonian region of Peru and Ecuador to the north of the Madre de Dios River in western Pando Bolivia (Heltne et al., 1981). This species has also been found to occur in South-western Brazilian Amazonia in the state of Rondonia, north of the Abuna River (Ferrari et al., 1999). This species prefers bamboo, mixed secondary, and scrub forests (Heltne et al., 1981). In the Andean foothills, this species occurs at a level up to 500 meters (Heltne et al., 1981). In Bolivia this species was always found in primary riverine forests, usually at heights ranging from 0 to 9 meters (Christen and Geissmann, 1994; Christen, 1999). In the dense lower levels of bamboo forests, this species prefers to live 1 to 3 meters above the ground (Davis, 1994).

ECOLOGY:
The diet of Goeldi's marmoset includes fruit, berries, insects, and spiders (Heltne et al., 1981). This species has been found to consume the fruit of Cecropia morassi (Heltne et al., 1981). This species was also found to consume fruit from the species Pseudolmedia macrophylla trecul and Pourouma cecropiaefolia (Buchanan-Smith, 1991). This species will forage at the tops of trees for fruit from the species Piptadenia sp. and Clarisia racemosa (Pook and Pook, 1981). Generally this species feeds at the lower levels of the forest and at the ground, but occasionally will forage for fruit in taller trees (Heltne et al., 1981). This species has been observed to eat cacao from plantations. Goeldi's marmoset will jump to the ground to capture insects (Heltne et al., 1981). Insects found to be consumed include moths and grasshoppers, and live animals tend to be eaten head first (Heltne et al., 1981). In the late dry season this species relies heavily on fruit from the genera Piptadenia and Cecropia (Pook and Pook, 1981). During the wet season groups will range further than the dry season in search of ripening fruit (Pook and Pook, 1981). This species obtains its water from pools found on the ground as opposed to licking it from leaves as is more commonly found in the callitrichids (Heltne et al., 1981).

This is a diurnal and an arboreal species. Group sizes for this species range from 5 to 8 individuals (Heltne et al., 1981). In Bolivia it was found that group sizes for this species ranged from 2 to 5 individuals (Christen and Geissmann, 1994). The group begins traveling during the day around mid-morning, and alternates between traveling, feeding, and resting for the rest of the day (Heltne et al., 1981). When traveling, groups tend to use certain routes and tend to use the outer parts of the home range (Pook and Pook, 1981). When resting, social grooming is an activity that frequently occurs (Heltne et al., 1981). This species will rest in subgroups of 1-4 individuals separated by several meters (Pook and Pook, 1981). Groups of Goeldi's marmosets tend to be isolated from each other separated by several kilometers (Pook and Pook, 1981). This species will sleep in trees 10 to 15 meters in height (Heltne et al., 1981). This species has found to sleep in groups in holes in trees (Masataka, 1981b). Groups have also found to sleep in dense thickets of vegetation (Pook and Pook, 1981).

LOCOMOTION:
This species moves quadrupedally through the forest. The basic gait is a gallop, from which a leap or a pounce may come from, especially when moving quickly towards a highly desirable food source (Heltne et al., 1981). This species also moves from vertical to vertical trunk by leaping, and this species prefers to move at the lower levels of the forest (Heltne et al., 1981). When leaping, this species will use its hindlimbs to generate momentum (Heltne et al., 1981). This species will leap from one cluster of thin branches to another over a distance of 6-8 meters (Christen, 1999). Goeldi's marmoset will descend trunks either head first like members of the genus Saguinus or backwards like the cebids do (Christen, 1999).

SOCIAL BEHAVIOR:
The Goeldi’s marmoset lives in groups of sizes from two to ten individuals. There is communal care of the offspring, usually by older offspring who have not left the group. This species has been shown in captivity to have a monogamous breeding system, although in the wild it may be polygynous (Carroll, 1988). Encarnacion and Heymann (1998) found that this species in the wild is polygynous. These older offspring are suppressed reproductively. Lyon et al. (1985) found that a two year old female was peripheralized in a group following a birth in the group. Carroll (1993a, 1993b) found that there is not any evidence for a lasting pair bond between males and females. Though not much agonism has been observed between males and females in pairs (Carroll, 1985). Contact and proximity within a pair is initiated and maintained at a higher frequency by the male more than by the female (Carroll, 1985). Males tend to guard their mates from predators and other conspecific groups (Carroll, 1985).

Goeldi's marmoset forms mixed-species associations with Saguinus fuscicollis and Saguinus labiatus (Pook and Pook, 1982; Christen and Geissmann, 1994; Buchanan-Smith, 1991). This species has also been found to form mixed-species associations with Callicebus moloch (Pook and Pook, 1982). There is a greater preference for this species to be associated with Saguinus fuscicollis rather than Saguinus labiatus (Pook and Pook, 1982). In Bolivia mixed groups of Goeldi's marmoset, Saguinus labiatus, and Saguinus fuscicollis would spend most of the day together, except for splitting during midday, then in late afternoon splitting up again to go to separate sleeping sites (Pook and Pook, 1982; Christen and Geissmann, 1994). These mixed groups would most often visit feeding trees during the early morning and mid-afternoon, and in late morning forage more for insects (Pook and Pook, 1982). These mixed groups maintained contact and spacing by the use of shrill calls (Pook and Pook, 1982). These shrill calls were most often heard early in the morning then decreased in frequency when the group comes together (Pook and Pook, 1982). Christen and Geissmann (1994) also studying mixed-species associations in Bolivia, noted that the three different species used soft contact and long calls upon emerging from sleeping sites. When moving, Goeldi's marmoset tends to always be the species in the rear of the mixed-species group (Pook and Pook, 1982). There is no direct competition between members of the mixed-species group because each species uses a different level of the forest for foraging and traveling (Pook and Pook, 1982).

Infants for the first two weeks are exclusively cared for by the female.
The female will transfer infants to the fathers about 3 weeks after birth and the father becomes an important caregiver for the infant, the infant returning mostly just to feed from the mother (Jurke and Pryce, 1994). Mothers become aggressive to infants between the ages of 2 to 5 weeks, helping to facilitate the transfer to the fathers (Jurke and Pryce, 1994). Female offspring tend to be transferred to their fathers earlier than male offspring (18 days versus 25.4 days) (Jurke and Pryce, 1994). Also male offspring were nursed longer as opposed to female offspring (2.4 times per hour versus 1.6 times per hour) (Jurke and Pryce, 1994). Paternal behavior may occur in Goeldi's marmoset because the demands of pregnancy and lactation are energy consuming for the female (Jurke and Pryce, 1994). Grooming of the infant has its highest occurrence in the fourth week, with the female performing a majority of the grooming (Masataka, 1981a). Infants will become more independent as non-mothers reject them (Masataka, 1981a).

Play tends to be an important behavior in infants and young, but this behavior is very rarely present in the behavioral repertoire of the adult (Heltne et al., 1981). In the young this behavior serves an exploratory and learning function (Heltne et al., 1981).

For Goeldi's marmoset the main predator is the Tayra, Eira barbara, which is a terrestrial carnivore (Christen and Geissmann, 1994). Another potential predator could be the jaguarundi, Herpailurus yaguarondi (Christen and Geissmann, 1994). This species was found to run down to the ground when a large buzzard would fly overhead (Pook and Pook, 1981).

VOCAL COMMUNICATION:quiet whistle: This call is soft, medium-pitched, and monosyllabic (Heltne et al., 1981). Between the notes there are long intervals, and the mouth is either closed or slightly open during this call, and the call can come thru the nostrils (Heltne et al., 1981). This common call is emitted by all individuals, and this heard during situations of rest and infant-mother vocalization (Heltne et al., 1981). This call serves to quiet, comfort, or reinforce the pair or family bond, and is responded to with relaxation or a quiet whistle (Heltne et al., 1981).

chirp: This call is a short, moderately loud, high-pitched whistle (Heltne et al., 1981). The mouth is closed or slightly opened when this call is emitted (Heltne et al., 1981). This common call is given by all members of the group, and this call is heard in situations of the discovery, selection, and eating of food and in the change of rest posture and movement (Heltne et al., 1981). This call functions to communicate presence, movement, or food, and this is responded to with vocalizations or approach (Heltne et al., 1981).

tchuck: This call is low pitched, short, and plosive in nature (Heltne et al., 1981). The notes of this call occur at irregular intervals and bipedal guard stance occurs with this call (Heltne et al., 1981). This call is rare and is performed by adults of both sexes, in particular more dominant individuals (Heltne et al., 1981). This call is heard in situations when approached by an intruder (Heltne et al., 1981). This call functions to communicate alertness to the group and to startle or threaten intruders, and is responded to by fleeing, attacking, or if the receiver is the mate of the sender, then the response could be a tchuck, song, or flee (Heltne et al., 1981). This call may correspond to the alarm calls, or D calls, as described by Masataka (1982).

scream: This call is a high-pitched scream of a long duration, and it the loudest call in Goeldi's marmoset's repertoire (Heltne et al., 1981). This common call is emitted by all members of the group (Heltne et al., 1981). This call is heard by dominant individuals when attack of or by an intruder, by subordinates when fleeing, and by infants when distressed or hungry (Heltne et al., 1981). This call is used to signal a threat, warn groups, or to attract attention, and this call is responded to by fleeing, attacking, or nursing or retrieving the infant (Heltne et al., 1981). This call may correspond to the warning calls, or E calls, as described by Masataka (1982).

two syllable ascending: This call is a two-note, low-high whistle having long intervals between succeeding calls (Heltne et al., 1981). This common call is emitted by all members of the group, and this call is heard during: rest, movement, infant-mother communication, food selection, and group chatter (Heltne et al., 1981). This call serves to communicate identity, position, activity, and this is also used to maintain group cohesion (Heltne et al., 1981). This call is responded to with two syllable ascending, relaxing, or approaching food (Heltne et al., 1981). This may the long-distance location calls, or A calls, as described by Masataka (1982).

twitter: This call is described as a "long series of rapid single notes slowing into disconnected single notes" (Heltne et al., 1981). This call is moderately high in pitch and variable in volume, and the mouth may be open during this call (Heltne et al., 1981). This common call is emitted by all members of the group, and this call is heard during: rest, movement, infant-mother communication, food selection, and group chatter (Heltne et al., 1981). This call serves to maintain contact over long distances and to maintain group cohesion (Heltne et al., 1981). This call is responded to with vocalizations (Heltne et al., 1981). This may be comparable to the long-distance contact calls, or B calls, as described by Masataka (1982).

chrrr: These are long calls that are often repeated and are loud, multi-pitched, and medium in range (Heltne et al., 1981). During this call the mouth is open and the teeth may be exposed (Heltne et al., 1981). This is a common call found to be emitted only by infants and is heard during weaning (Heltne et al., 1981). This call functions to induce nursing or maternal contact, and the mother may respond by nursing, offering food, contact, or withdrawal and the male may respond by retrieving the infant (Heltne et al., 1981). This call may correspond to the H calls emitted by infants as described by Masataka (1982).

multisyllable ascent: This call is a sequence of 6 to 8 loud ascending notes that may be repeated, and the final note may end with multiple repeats (Heltne et al., 1981). This call is moderately common and is emitted by adult males and females and by juveniles of both sexes (Heltne et al., 1981). This call is heard in situations of isolation, marking, and agonistic encounters (Heltne et al., 1981). This call functions to maintain contact over distances and to relieve tension (Heltne et al., 1981). This call is responded to with vocalizations (Heltne et al., 1981).

song: During this call the mouth is open wide and the neck is extended (Heltne et al., 1981). This call is long, loud, rhythmic and has components that occur in the following sequence: "1. ascending scale 2. sustained highest final note 3. descending 6-8 note scale 4. sustained lowest final note 5. two-syllable ascending call" (Heltne et al., 1981). This call is rare and it is emitted by adult males and females, and this call is heard during active marking sequences, death of an infant, and food discovery (Heltne et al., 1981). This call functions to indicate food source, social status, identity, territory, and as a warning signal (Heltne et al., 1981).

shrill call: This is a loud call that has a frequency range of 6 to 10 kilohertz, and the mouth opened wide when this call is emitted (Pook and Pook, 1982). This call is also described as consisting "of a series of 11-13 elements emitted over a period of about 3-4 s, each one slightly lower in pitch, longer in duration, and softer in amplitude than the previous one" (Pook and Pook, 1982). This call can carry a distance of 100 meters or more (Pook and Pook, 1982). This call functions to coordinate movements with other species, e.g. Saguinus labiatus and Saguinus fuscicollis, in a mixed-species group (Pook and Pook, 1982).

OLFACTORY COMMUNICATION:sneeze: This is a nasal exhalation where exudate is propelled at a horizontal or vertical substrate (Heltne et al., 1981). This may be quiet or forced and can be single or occur in series, and the eyes are closed during this pattern (Heltne et al., 1981). This behavior is very common and is performed by all members of the group, adult females perform this more during estrus (Heltne et al., 1981). This behavior is seen during seated rest and prior to or with dorsal, anal, and nose rubs (Heltne et al., 1981). This behavior functions to clear nasal passages, provide marking discharge, and to mark the core area (Heltne et al., 1981).

nose rub marking: This behavior is a forced rubbing of the nose, cheek, and upper lip against a vertical or horizontal substrate (Heltne et al., 1981). This behavior is very common and is performed by all members of the group and especially adult females during estrus (Heltne et al., 1981). This behavior occurs in many different social contexts (Heltne et al., 1981). This behavior functions to mark the core area, self, or the mate and may be also used to release tension (Heltne et al., 1981). This behavior may stimulate similar marking behavior in conspecifics (Heltne et al., 1981).

sneeze-nose rub: This behavior is nose rub marking with sneeze occurring with it (Heltne et al., 1981). This common behavior is performed by adult males and females and juveniles of both sexes, and this is seen in situation of seated resting, marking locations, agonistic interactions, and on environmental alterations (Heltne et al., 1981). This behavior functions to clear nasal passages, provide a marking discharge, mark the core area, release individual tension, and serve as a displacement behavior (Heltne et al., 1981). The response to this behavior may be to induce marking in other individuals (Heltne et al., 1981).

scent licking: This is when the tongue is flicked outside of the mouth and usually it is quick and occurs singly (Heltne et al., 1981). The mouth is slightly open during this pattern (Heltne et al., 1981). This common behavior is performed by all members of the group and is seen during situations when an individual comes upon an unfamiliar object or animals, urine, or another type of marking, and towards the tail or rump of a mate during seated rest (Heltne et al., 1981). This pattern functions to sense chemical signals (Heltne et al., 1981).

dorsal rub: This is when an individual will rub the head, shoulder, and/or back against a vertical support (Heltne et al., 1981). During this the hands are limp at the wrist or are scratching the ischium, and the individual may sneeze (Heltne et al., 1981). This behavior is moderately common and is performed by adult males and females (Heltne et al., 1981). This pattern functions to spread the core area scent marks on the substrate and on the pelage and also found during autogrooming (Heltne et al., 1981). This pattern may induce marking by other individuals (Heltne et al., 1981).

urine marking: This when an individual releases one or more drops of urine from a quadrupedal stance (Heltne et al., 1981). This common behavior is performed by all members of the group, males more than females, and is done in commonly marked areas, environmental alterations, and in marking sequences (Heltne et al., 1981). This pattern functions to mark the core and peripheral areas, and this may induce other individuals to mark (Heltne et al., 1981).

tail wafting: This is when an individual will hold the tail at or above the level of the body, and have the tail arched (Heltne et al., 1981). This pattern is performed during slow walk and this is common during urine marking (Heltne et al., 1981). This behavior is performed by adult males and females and occurs in situations of urine marking and during estrus the female will do this in front of her mate (Heltne et al., 1981). This pattern functions to spread the scent and in the case of the female to signal receptivity (Heltne et al., 1981). This behavior may be responded to with either ignoring, courting, or mounting (Heltne et al., 1981).

anal rub: This is when an individual will rub the anogenital skin on a horizontal substrate in a seated position (Heltne et al., 1981). Scream may accompany this behavior during agonistic contexts (Heltne et al., 1981). This common behavior is performed by adult males and females, and the dominant male will perform this behavior first (Heltne et al., 1981). This behavior is performed in commonly marked areas, environmental alterations, and during agonistic situations (Heltne et al., 1981). This pattern functions to mark the core and peripheral areas and to release tension (Heltne et al., 1981). This may stimulate others to engage in marking behavior (Heltne et al., 1981).

sternal rub: This is when an individual will rub the sternal glands on a horizontal surface from a low crouch posture (Heltne et al., 1981). This behavior is rare and is performed by both adult males and females, with the frequency for the female increasing during estrus (Heltne et al., 1981). This behavior occurs in areas that are heavily scented (Heltne et al., 1981). For the male this behavior functions to mark the territory and for the female this pattern functions to indicate sexual receptivity (Heltne et al., 1981).

pub-abdominal rub: This is when the abdomen and pubis in the female and the abdomen, pubis, scrotum, tip of penis, and thigh are pulled along the substrate, with the chest off of the substrate and the hindquarters depressed (Heltne et al., 1981). This behavior is rare and is performed by both adult males and females, with the frequency for the female increasing during estrus (Heltne et al., 1981). This behavior occurs in areas that are heavily scented (Heltne et al., 1981). For the male this behavior functions to mark the territory and for the female this pattern functions to indicate sexual receptivity (Heltne et al., 1981).

half tail mark: This is the coiled tail is swept against the anogenital region from a quadrupedal stance (Heltne et al., 1981). This behavior is moderately common and is performed by adult males and females, with estrous females performing this pattern most frequently (Heltne et al., 1981). This behavior occurs prior to rest, during allogrooming, during estrus, and during environmental alterations (Heltne et al., 1981). This behavior serves to self-mark and mark the sleeping site, solicit grooming, and mix and distribute glandular secretions, and also in the female this serves to indicate sexual receptivity (Heltne et al., 1981). This behavior may stimulate grooming or copulation (Heltne et al., 1981).

full tail mark: This is like half tail mark except the tail also sweeps the pubic, abdominal, sternal, and manubrial fields (Heltne et al., 1981). This behavior is moderately common and is performed by adult males and females, with estrous females performing this pattern most frequently (Heltne et al., 1981). This behavior occurs during allogrooming, during estrus, and during environmental alterations (Heltne et al., 1981). This behavior serves to self-mark and mark the sleeping site, solicit grooming, and mix and distribute glandular secretions, and also in the female this serves to indicate sexual receptivity (Heltne et al., 1981). This behavior may stimulate grooming or copulation (Heltne et al., 1981). Carroll (1985) found this behavior to be one of the most frequent scent-marking behavioral patterns.

VISUAL COMMUNICATION:stare: This is when an individual has the eyes wide open looking directly at the stimulus (Heltne et al., 1981). This common behavioral pattern is performed by dominant individuals more frequently (Heltne et al., 1981). Stare functions to communicate a threat on the part of the sender, and this is responded to by looking at or away from the sender or threatening the sender (Heltne et al., 1981).

yawn: This is when an individual will open the mouth widely, with tongue elevation often occurring (Heltne et al., 1981). This common behavioral pattern is performed by all individuals and is seen during rest periods (Heltne et al., 1981). This pattern functions to rouse or relax a mate and may elicit a vocalization or yawn from the receiver (Heltne et al., 1981).

brow lowering: This is when an individual will draw the brow down, with the nose furrowed and the crown hairs erect (Heltne et al., 1981). This common behavioral pattern is performed by all individuals and is seen in hostile situations (Heltne et al., 1981). This pattern serves to communicate a moderate threat on the part of the sender, and may elicit a withdrawal on the part of the receiver (Heltne et al., 1981).

tense mouth: This is when an individual has the mouth halfway open, with the lips tense and the tips of the canines exposed (Heltne et al., 1981). This behavior is rare and is performed by all individuals during hostile situations (Heltne et al., 1981). This pattern serves to communicate threat on the part of the sender and often occurs with tchuck vocalizations (Heltne et al., 1981). The receiver will either attack or flee (Heltne et al., 1981).

grimace: This is when an individual has the lips drawn back to exposed clenched teeth and also having the head low (Heltne et al., 1981). This behavior is rare and is performed by all members of the group, particularly subordinate individuals, and occurs during attacks by more dominant individuals (Heltne et al., 1981). This pattern serves to communicate appeasement on the part of the sender and usually the attacker will halt the attack (Heltne et al., 1981).

tongue flick: This is when an individual has the mouth opened very slightly and the tongue is extended and withdrawn repeatedly (Heltne et al., 1981).This behavior is rare and is performed by mated adult males and females and is seen in situations where members of the same sex are intruding (Heltne et al., 1981). This pattern serves to communicate an intense threat on the part of the sender and the receiver may withdraw or become peripheralized (Heltne et al., 1981).

open mouth teeth exposed: This is when an individual opens the mouth widely and has all of the teeth exposed (Heltne et al., 1981). This behavior is rare and is performed by adult males and females and juveniles of both sexes, and this occurs in extremely hostile situations (Heltne et al., 1981). This pattern serves to communicate intense threat mixed with appeasement, and the receiver may respond to this behavior by fleeing or attacking (Heltne et al., 1981).

bipedal guard stance: This is when an individual will stand bipedally with the hands on the vertical support, the eyes focused on the stimulus, and emitting the tchuk vocalization (Heltne et al., 1981). Dominant individuals performing this behavior may arch the body over or behind the mate (Heltne et al., 1981). This behavior is common and is performed by adults of both sexes, and this is seen in response to a direct threat by intruders or as a response to alarm calls (Heltne et al., 1981). This pattern functions to frighten and to assist in investigation, and the response to this behavior may include retreating or staring at or moving toward intruder (Heltne et al., 1981).

bipedal threat: This is when an individual is standing unsupported in a bipedal fashion with the ventrum exposed, the hairs piloerected, and the brows lowered (Heltne et al., 1981). Tail hair may be independently piloerected from body hair (Omedes and Carroll, 1980). Tense mouth can occur with this display (Heltne et al., 1981). This behavior is rare and is performed by adults of both sexes, in particular dominant individuals (Heltne et al., 1981). This display is seen in situations of attacking and threat (Heltne et al., 1981). This pattern functions to communicate an offensive threat, and the response by the receiver may either be retreat or attack (Heltne et al., 1981).

quadrupedal threat-attack stance: This is when an individual will be in a quadrupedal position where the back is arched, the elbows and knees almost fully extended, piloerection of the hairs, and the brows are lowered (Heltne et al., 1981). Tense mouth may occur with this display (Heltne et al., 1981). This behavior is rare and is performed by the more dominant individual (Heltne et al., 1981). This display is seen in situations of attacking and threat (Heltne et al., 1981). This pattern serves to communicate anger and this helps to make the individual appear larger (Heltne et al., 1981). The receiver of this display will either withdraw or attack (Heltne et al., 1981).

grooming solicitation crouch: This is when an individual crouches, lowers the head so that it is lower than the rump, and points the eyes forward (Heltne et al., 1981). This common behavior is performed by adult males and females and juveniles of both sexes and is seen in relaxed social situations (Heltne et al., 1981). This pattern serves to communicate permission to groom and will be responded with ignoring, grooming, or placing the hand on the back of the sender (Heltne et al., 1981).

uncoil tail: This is when an individual will uncoil and recoil the tail between the legs from a seated position (Heltne et al., 1981). This behavior is very common and is performed by adult males and females during resting periods (Heltne et al., 1981). This pattern is used to communicate the desire to have one groom the tail and will be responded with either ignoring the sender or grooming the tail (Heltne et al., 1981).

solicit mounting: This is where the adult female will be a crouching position facing the male, looking at him (Heltne et al., 1981). This behavior is common during estrus and serves to elicit copulations (Heltne et al., 1981). The male will either mount or ignore the female (Heltne et al., 1981).

TACTILE COMMUNICATION:contact sitting: This is when two individuals are sitting side by side, parallel head to head, or angled often sitting on uncoiled tails (Heltne et al., 1981). This common behavior is performed by all members of the group and usually occurs in situations of sleep or rest (Heltne et al., 1981). This behavior functions to establish and reinforce the pair bond, provide safety and warmth, and this will often receive a response of posture adjustment (Heltne et al., 1981).

social grooming: This is where one individual will groom a conspecific, removing dead skin and parasites. An individual wishing to be groomed will lower the rump, thorax, or head in front of the groomer (Heltne et al., 1981). The groomer will use the hands to groom a few hairs at a time, and will occasionally use the teeth or tongue to nibble or lick at the skin underneath the hairs (Heltne et al., 1981). The areas the groomer focuses on the most are the saddle, back, the side of the thorax, outer thighs, and areas on the face (Heltne et al., 1981). Parts of the face, e.g. eyes, mouth, nostrils, tend to be groomed in a rough manner (Heltne et al., 1981). The groomer may also bite groom the manubrial gland of the groomee (Heltne et al., 1981). The groomee is often in a seated position with the tail curled forward between the limbs (Heltne et al., 1981). In the wild this occurs around the noon rest period and the type of grooming is reciprocal where first one will groom another then the two will swap roles (Heltne et al., 1981).

fight: This is when individuals will push, cuff, bite, or wrestle with one another for brief episodes (Heltne et al., 1981). This behavior is very rare and is performed by adult males and females, and this pattern occurs in situations of competition for food, dominance interactions, unreceptive female, and during weaning (Heltne et al., 1981). This behavior functions to repel, escape, or dominate, and this receives a response of either cease, submit, or withdraw (Heltne et al., 1981).

REPRODUCTION:
This species gives birth to a single offspring, which differs amongst other callitrichids, twice a year (Fleagle, 1988). Twins have been noted to be born in captivity (Altmann et al., 1988). During the estrus period, the female is receptive for a mean length of seven days (Heltne et al., 1981). Gestation length for this species is 145-152 days (Carroll, 1993b).

The female will solicit copulations from the male by first stretching before the male then lifting the tail as she rises, exposing the genitoanal region and the base of the tail (Heltne et al., 1981). The female will pass repeatedly before the male, passing a dampened tail before the nose of the male (Heltne et al., 1981). Then the female will drop her head in front of the male facing him (Heltne et al., 1981). The male will then start grooming the female's crown then move to the back, followed by sniffing, nose rubbing, or licking the arch of the back (Heltne et al., 1981). The male then moves to a posterior position, behind the rump of the female, with the female raising her rump up towards the male (Heltne et al., 1981). If the female allows intromission, she will flatten her back, positioning the vulva for more easy access for the male (Heltne et al., 1981). During this time the female may lick towards the male or reach back and grab the arm or shoulder of the male and gentle pull at them (Heltne et al., 1981). Intromission is followed by a small number of thrusts, and ejaculation occurs during thrusting with the thighs and pelvis of the male quivering (Heltne et al., 1981). The male, during these thrusting bouts, may nose rube or lick the back of the female or scent lick the air (Heltne et al., 1981). After ejaculation, the male and female will lick and examine their respective genitals (Heltne et al., 1981).

Masataka, N. 1981a. A field study of the social behavior of Goeldi's monkeys (Callimico goeldii) in North Bolivia: I. Group composition, breeding cycle, and infant development. Kyoto University Overseas Research Reports of New World Monkeys II.

Masataka, N. 1981b. A field study of the social behavior of Goeldi's monkeys (Callimico goeldii) in North Bolivia: I. Grouping pattern and intragroup relationship. Kyoto University Overseas Research Reports of New World Monkeys II.